A Unihedron Sky Quality Meter (SQM) is an instrument used to measure the luminance of the night sky. It is used to quantify the skyglow aspect of light pollution and uses units of "magnitudes per square arcsecond”.
A scale was formulated between the numbers of 16.00-22.00. At the lowest number—16.00—the sky is the brightest. Meanwhile, a number of 22.00 represents the least luminance—the least light pollution.
Mpsas Interpretive Scale
Since November 2023, IAO, Hanle has employed a Sky Quality Meter, which is mounted at the observatory. This device is set to automatically log data every 5 seconds, with its power activation and deactivation aligned with astronomical twilight. Furthermore, a plot is produced each morning that encompasses the data from the previous night, spanning from evening to morning astronomical twilight.
To learn about the system; visitSky Quality Monitor System at IAO Hanle
SQM Readings on 4 Oct 2010
SQM Installed on top of the mountain
SQM Readings on 22 Mar 2024